Thread: How do I tell which transformer I need

Arry,

Have a look at these.

Jaycar Electronics - Search results

Once you get the unit look at the power ratting. Probably in watts. Divide that number by 115 and that will give you how many amps the stepdown transformer needs to supply. Then for the list above select the one that it nearest but above what is required.

Jaycar have outlets in Perth so it shouldn't be a problem in obtaining one once your drill arrives.

A lot of the current battery chargers will work on a range of voltages Arry so I wouldn't buy a transformer until you've checked the unit.

As an example, my Canon camera Lithium Ion battery charger has a stated input voltage range of 100 - 250V AC so all that is needed for worldwide operation is just a plug adaptor.

Hopefully the Bosch one uses the same technology.

Bit of iffy info here sorry. You need a 18V charger, The Amps are not a huge concern as long as its a reasonably big charger as its charging batteries. Now your issue is A/ what fittings you need to fit the drill or the battery. Now if you pull the battery out of the drill to charge it, the connections are DC. B/ If you plug the charger into the drill, it may be that you have an electronics circuit in the drill which rectifies the voltage and supplies the correct charge to the battery. In that case all you need is a transformer supplying about 18V AC.
If it comes with a charger, then Steve may be correct, it may be universal, if not they you need a step down transformer from 240 to whatever it is.
So my advice is you need to find out what is required from the manufacturer, get it wrong could result in a lot of smoke

Originally Posted by rrobor

If it comes with a charger, then Steve may be correct, it may be universal

Don't get your hopes up because I just checked my Australian bought one and it is 240v only. New chargers seem to be $99 on eBay but you would have thought somebody would have an old one kicking about.

My charger is 50 watts so you could use something like the 100 watt one from:

step down tranformers american to australia stepdown 110v 120v to 240v

for $42.90

Advantage of that is you are right for any more gear you buy from the US.

I would assume it should come with a charger.

Contact amazon to find out for sure before buying anything else.

Make sure it is 240v input and not 220vUS.

Originally Posted by Glennet

Don't get your hopes up because I just checked my Australian bought one and it is 240v only. New chargers seem to be $99 on eBay but you would have thought somebody would have an old one kicking about.

That's a shame, my next suggestion was to go looking for a local version of the charger but at $99 it probably is better value to get the stepdown for it's possible additional uses.

Two ways to look at the issue.

Quicky way. Product description indicates that unit has a charger and two 1.3AH batteries and charges them form flat in 30 minutes. From experience with my Mak equivalent gear, I need a 250VA stepdown transformer for 25 minute charging 3.0AH batteries with the Mak fast charger. Scaling down on battery capacity, a stepdown of about 120-150VA would be suitable and have a modest degree of reserve for use with slightly higher consumption gear.

Slower way. Wait till it arrives and read the label on the charger, looking for either the required current, or watttage. If current is listed, multiply current by 120V to get VA rating. If watttage is listed multiply by 1.2 to get VA, this a power factor correction.

Don't try to do basic calcs based on battery voltage, AH capacity and time, as this will not factor charge efficiency (how much charge supplied to the battery pack is recoverable for use), charger overheads (how much power supplied to the charger is used internally and how much is transfered to the battery).

Try to get a true isolated transformer rather than an autotransformer unit. Slightly more expensive but definitely safer long term . Jaycar should be able to come up with one, there may be others in your area. In Melbourne I would suggest Radio Parts group.

If anyone requires a good hefty 240 to 120 volt stepdown transformer I have a very good one you just plug into Aussie 240 and the is a socket on to to give you 120 volts. Comes in a proper purpose made case. I'm willing to exchange it for a 5 amp or more battery charger or anything which outputs any voltage from 14 to 40.DC. Even a transformer from a burnt out battery charger as long as the transformer is OK. I don't recall the wattage of the stepdown but it's more than enough to power a TV or a large HiFi unit.

Unfortunately for me the chance of the unit you get being universal is pretty good. Just about everything made today comes with either 240/120 volts and 50/60 hertz. All auto switching. It saves the manufacturers a fortune by not needing different units for different countries. The stepdown is brand new but has sat in a cupboard for a while. there's nothing to wear out though.

Regards Stu